DE 197 03 903 A1 describes a steering system in a motor vehicle, at which a steering wheel angle is transferred on a steering linkage by a steering shaft and a transmission, which is coupled cinematically with the steered wheels of the vehicle and which adjusts the wheels with the desired steering angle. For a steering support an electric servo engine is provided, which initiates a supporting moment over the steering linkage. The height of the supporting moment depends on different factors, amongst other on the hand moment that is initiated by the driver, if necessary also on other vehicle parameters and state variables as for example the vehicle speed.
The information about the variable of the steering angle, which is preset by the driver over the steering wheel, is furthermore required for diverse electronic regulating and controlling systems in motor vehicles. For determining the actually adjusted steering angle a touch-less working rotation angle sensor is provided according to DE 197 03 903 A1, which is construed for detecting a magnetic field, which is created by a magnet that is connected torque-proof with the steering shaft. The magnet is arranged next to the steering pinion, which sits at the front side of the steering shaft and which transfers the steering movement over the transmission on to the steering linkage. The sensor is located on the other hand in the transmission housing. The size of the steering angle is calculated as a function of the circulating magnetic field that is created by the magnet. But hereby it has to be considered that the steering wheel can carry out multiple circulations, which makes the information over the average or initial zero position of the steering shaft necessary for the accurate determination of the actual steering angle variable.